Deformable spindle end portion

ABSTRACT

A hub ( 2 ) includes a spindle ( 14 ) which projects through a housing ( 4 ) and rotates relative to the housing ( 4 ) on a bearing ( 6 ) that is located between the spindle ( 14 ) and the housing ( 4 ). The bearing ( 6 ) has two sets of raceways ( 28,40 ) that are oblique to the axis x, and in addition rolling elements ( 36 ) arranged in two rows between the sets of raceways ( 28,40 ). The inner raceways ( 28 ) that fit around the spindle ( 14 ) and have back faces ( 32 ), with the back face ( 32 ) for one of the races ( 26 ) being against a shoulder ( 18 ) from which the spindle ( 14 ) projects. Initially, the end of the spindle ( 14 ) projects straight beyond the back face ( 32 ) of the outer race—indeed, so that the races ( 26 ) can be installed over the spindle ( 14 ). But once the housing ( 4 ) and races ( 26 ) are in a position around the spindle ( 14 ), the projecting end portion of the spindle ( 14 ) is deformed radially and axially in a rotary forming operation such that it transforms into a formed end ( 20 ) that lies behind back face ( 32 ) of the race ( 26 ). With the two races ( 26 ) between the formed end ( 20 ) and the shoulder ( 18 ). During the rotary forming operation the hub ( 26 ) rotates, and the end of its spindle ( 14 ) is forced against a rotating forming tool and the force is monitored. The housing ( 4 ) is restrained and the torque transferred from the rotating hub ( 2 ) to the housing ( 4 ) is monitored.

RELATED APPLICATIONS

This is a division of U.S. Ser. No. 09/446,671 filed Dec. 23, 1999, U.S.Pat. No. 6,443,622, which is a 371 of PCT/GB98/01823 filed Jun. 22,1998.

BACKGROUND OF THE INVENTION

This invention relates in general to machine components having anantifriction bearing between them for enabling one component to rotaterelative to the other and, more particularly, to a rotary formingprocess and machine for uniting the machine components and the bearing.

Several basic arrangements exist by which the road wheels of automotivevehicles are attached to the suspension systems of such vehicles, andall involve a rotatable hub of one type or another. In one arrangement,the hub has a drive flange, and a spindle which projects from theflange. The spindle rotates in a housing on an antifriction bearing. Thehousing is bolted to the suspension system of the vehicle, while theroad wheel is bolted to the flange of the hub. Thus, the hub and roadwheel rotate relative to the housing and suspension system with minimumfriction. The bearing has angular raceways which are oriented such thatthey take thrust loads in both axial directions as well as radial loads.Typically, the bearing has inner races mounted on the spindle androlling elements arranged in two rows between raceways on the innerraces and more raceways in the housing. A nut threads over the end ofthe spindle to retain the inner races on the spindle, and this has theeffect of holding the entire arrangement together, that is, unitizingthe hub assembly.

But the threads require an extra machining operation in the manufactureof the hub and the installation of the nut represents another assemblyoperation. These operations are reflected in the ultimate cost of thehub assembly. Furthermore, a nut may work loose and disrupt the settingof the bearing, perhaps causing wheel wobble and damaging the seals thatisolate the interior of the bearing and disrupt the setting of thebearing, perhaps causing wheel wobble and damaging the seals thatisolate the interior the bearing.

Others have employed a rotary-formed bead at the end of a hub spindle tohold a hub assembly together. But forming the bead, at least against theback face of the inner race for an antifriction bearing, requiresprecision and close monitoring of the forming operation to ensure thatthe forming operation does not distort the bearing and detract from itsoperation.

SUMMARY OF THE INVENTION

The present invention resides in a process for uniting two machinecomponents and a bearing that is between the components for enabling onecomponent to rotate relative to the other component. The bearing mayhave raceways that lie oblique to the axis of rotation and two rows ofrolling elements, with the arrangement being such that the rollingelements transmit both radial and axial loads between the components. Atleast one of the raceways is on a race that is fitted to one of themachine components. Initially, that machine component projects beyondthe race without obstructing the race, but thereafter the end of thecomponent is radially and axially deformed in a rotary forming operationto produce a formed end which lies behind the race and utilizes theassembly. During the rotary forming operation, the component that isdeformed rotates, relative to the other component, against aforming-tool. Preferably, the other component is restrained. The torquetransferred from the rotating component to the stationary component maybe monitored. For example, one of the components includes a flange whichis held stationary such that the flange serves as a torque arm.

The present invention further provides a machine for uniting first andsecond machine components and a bearing that is between the componentsto enable one component to rotate relative to the other component aboutan axis of rotation, the bearing including raceways and rolling elementsarranged in at least one row between the raceways, such that the rollingelements transmit radial and axial loads between the machine components,the bearing including a separate race that is fitted to the secondcomponent with the second component initially extending beyond a backface on the race in provision of an end portion, said machinecomprising: a table that rotates about an axis and is configured toreceive and engage the second machine component with that axis of thebearing and the axis of the table coincident, whereby the secondcomponent rotates with the table: a restraining member configured toengage the first machine component and prevent it from rotating with thesecond component: a head located axially beyond the table, but presentedtoward the table and having a spindle that rotates; and a forming toolcarried by the spindle of the head and configured to radially andaxially deform the end portion of the second component when the tableand head are brought toward each other, with deformation causing themetal of the end portion to flow behind the back face of the separaterace for the bearing, whereby the machine unites the first and secondcomponent and the bearings.

In a separate aspect the present invention provides a bearing unitizedbetween two machine components manufactured in accordance with the abovedescribed process, wherein an end portion of one of the machiningcomponents is radially and axially deformed about the outer surface ofone end of the bearing, a portion of the outer surface of the deformedend describing a substantially flat clamping surface.

In a further aspect the present invention provides a machine componentfor use in the above described process, the machine component having anend portion with a substantially flat inner surface and an outer surfaceformed from a plurality of tapered surfaces each at different angles tothe axis of rotation of the component. Preferably, the outer surface ofthe end portion is described by three connecting tapered surfaces withthe middle tapered surface being at a smaller angle to the axis ofrotation than the outer two tapered surfaces.

The invention also consists in the parts and in the arrangements andcombination of parts hereinafter described and claimed.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of a hub assembly unitized with a formed endin accordance with the present invention;

FIG. 2 is an end view of the hub assembly taken along line 2—2 of FIG.1;

FIG. 3 is an enlarged partial sectional view of the formed end thatunitizes the hub assembly;

FIG. 4 is a partial sectional view of an end portion prior todeformation into the formed end of FIG. 3;

FIG. 5 is a front elevational view of the machine for deforming the endportion illustrated in FIG. 4 into the formed end illustrated in FIG. 5;

FIG. 6 is a sectional view of the machine taken along line 6—6 of FIG.5; and

FIGS. 7A B, and C are sectional views in elevation showing the tool fordeforming the end portion and sequentially illustrating thedeformations.

Corresponding reference numerals will be used throughout the severalfigures of the drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way ofexample and not by way of limitation. This description will enable oneskilled in the art to make and use the invention, and describes thatwhich is presently believed to be the best mode of carrying out theinvention.

Referring now to the drawings, a hub assembly A (FIG. 1) for attaching aroad wheel for a vehicle to the suspension system of the vehicleincludes a hub 2, a housing 4 and a bearing 6 which enables the hub 2 torotate relative to the housing 4 about an axis X of rotation withrelatively little friction. A road wheel and a brake disk are attachedto the hub 2, while the housing 4 is secured firmly against a componentof the suspension system for a vehicle.

The hub 2 (FIG. 1) has a flange 10, a short pilot diameter 12 on oneside of the flange 10 and a spindle 14 on the other. Both the pilotdiameter 12 and the spindle 14 lie along the axis X. The flange 10contains lug bolts 16 which project axially from it in the direction ofthe pilot diameter 12, but lie radially outwardly from it. The pilotdiameter 12 functions as a pilot for aligning the wheel with the hub 2as the wheel is advanced against the flange 10, to which it is securedwith lug nuts that thread over the bolts 16. The spindle 14 merges froma shoulder 18 set inwardly from the inside face of the flange 10 andterminates in a formed end 20 located at its opposite end. The spindle14 contains a bore 22 which opens out of it at the formed end 20.

The bearing 6 includes (FIG. 1) an inner race in the form of two cones26 which fit around the spindle 14 where they are captured between theshoulder 18 and the formed end 20, there being an interference fitbetween each cone 26 and the spindle 14. Each cone 26 has a taperedraceway 28 that is presented outwardly away from the axis X, a thrustrib 30 at the large end of its raceway 28, and back face 32 that issquared off with respect to the axis X on the end of the thrust rib 30.The inboard cone 26 is somewhat longer than the outboard cone 26 byreason of a cylindrical cone extension 34 which projects beyond thesmall end of its raceway 28. The inboard cone 26 at its cone extension34 abuts the small end of the outboard cone 26 along the spindle 14,that is to say, the two cones 26 abut their front faces. The back face32 of the outboard cone 26 abuts the shoulder 18 that lies immediatelyinwardly from the flange 10. The formed end 20 outwardly beyond theinboard cone 26 and lies against the back face 32 of that cone. Thus,the two cones 26 are captured on the spindle 14 between the shoulder 18and the formed end 20. The two cones 26 abut their opposite ends, thatis at their front faces, so that the extension 34 lies between theraceways 28 out of the two cones 26.

In addition to the cones 26, the bearing 6 includes tapered rollers 36arranged in two rows, there being a separate row around each cone 26.Actually, the rollers 36 extend around the raceways 28 for the cones 26with their tapered side faces along the raceways 28 and their large endface against the thrust ribs 30. The rollers 36 of each row areessentially on apex, which means that the envelopes in which theirtapered side faces lie will have their apices located at a common pointalong the axis X. Each row of rollers 36 has a cage 38 to maintain theproper spacing between the rollers 36 in that row.

The ring-like housing 4 surrounds the spindle 14 as well as the twocones 26 and the two rows of rollers 36. It forms part of the bearing 6in that it has tapered raceways 40 which are presented inwardly towardthe axis X. Indeed, the housing 4 constitutes the outer race of thebearing 6. The raceways 40 on the housing 4 taper downwardly toward anintervening surface 42 which separates them. The rollers 36 likewise liealong the raceways 40 of the housing 4, contacting the raceways 40 attheir tapered side faces. At their large ends, the raceways 40 open intoshort end bores 44 in which the thrust ribs 30, of the two cones 26 arelocated.

Generally midway between its ends, the housing 4 has a triangular flange46 (FIG. 2) which fits against a component of a suspension system for avehicle. Here the housing A is secured firmly to the suspension systemcomponent with bolts that engage threaded holes 47 located in the lobesof the triangular flange 46. Along one of the edges of the triangularflange 46 the housing 4 contains a bore 48 (FIG. 1) which extendsinwardly, obliquely to the axis X, and opens into the interior of thehousing 4 through the intervening surface 42.

The oblique bore 48 contains a speed sensor 50, the inner end of whichis presented toward an excitor ring 52 that fits over the extension 34at the small end of inboard cone 26. Thus, the excitor ring 52 liesbetween the two rows of rollers 36. The ring 52 has teeth or otherdisruptions which cause the sensor 50 to produce a pulsating signal asthose disruptions move past the end of the sensor 50, and this of courseoccurs as the spindle 14 and the cones 26 around it rotate. Thefrequency of the signal reflects the angular velocity of the spindle 14and indeed the entire hub 2.

The end bores 44 in the housing 4 contain seals 54 which fit around thethrust ribs 30 on the cones 26 to establish dynamic fluid barriers atthe ends of the housing 4. These barriers isolate the rollers 36 and theraceways 28 and 40 from road contaminants, such as water, ice-meltingsalts and dirt.

The formed end 20 lies behind the back face 32 of the inboard cone sothat the two cones 26 are captured between shoulder 18 and the formedend 20 with their small ends in abutment. This not only retains the cone26 in the spindle 14, but also retains the housing 4 and rollers 36 inplace, this being attributable to the tapered geometry. In short, theformed end 20 unitizes the hub 5 assembly A.

More specifically, the formed end 20 wraps around the inboard cone 26 ata profiled or curved inside corner 56 (FIG. 3) and immediately outwardlyfrom the corner 56 has a flat inside end face 58 that lies along theback face 32 of the inboard cone 26. On its opposite side, the formedend 20 has a curved outside end surface 60 which merges with a flatoutside end surface 62 that lies perpendicular to the axis X. The curvedoutside end surface 60 and the flat inside end face 58 are connectedthrough a relatively sharp, yet curved, outside corner 64. The flatoutside end surface 62 merges into a first beveled surface 66 which liesat an oblique angle with respect to the axis X and the beveled surface66 merges into another second beveled surface 68 located at a somewhatsteeper angle to the axis X. The steeper beveled surface 68 leads intothe bore 22. The outside corner 64 lies radially at or slightly inwardlyfrom the large end of the raceway 28 on the inboard cone 26. The flatoutside end surface 62 provides a clamping surface for the hub assemblywhen clamped against a constant velocity joint or other such member.

The hub 2 does not always have the formed end 20. Initially, it existsas a pre-form 70 (FIG. 4), which is the condition in which it forged andthen machined. In the pre-form 70 the spindle 14 is straight, that is tosay, its cylindrical exterior surface continues axially to the very endof the spindle 14. The two cones 26, the rollers 36 of the two rows, andhousing 4, which is captured by the rollers 36, are all installed overthe straight spindle 14 of the pre-form 70, leaving an end portion 71 ofthe spindle 14 projecting beyond the inboard cone 26. Thereupon, theprojecting end portion 71 is deformed radially outwardly and axiallyinto the formed end 20 in a rotary forming operation (FIG. 7).

In the pre-form 70, the spindle 14 has (FIG. 4) the first beveledsurface 68 that leads away from the bore 22. The beveled surface 68merges into a slightly tapered surface 72 at a corner or circle C oftransition. The slightly tapered surface 72 merges into another taperedsurface 74 leads of greater angle. The steeper tapered surface 74 leadsout to a flat end surface 78 with which it merges at a curved surface80. The flat end surface 78 at its periphery has a chamfer 82.

That end portion 71 of the pre-form 70 initially projects beyond theback face 32 of the inboard cone 26 without change in its externaldiameter, but is thereafter transformed into the formed end 20 in arotary forming procedure. (FIG. 7). In this procedure the metal of theend portion 71 flows radially and axially, all without acquiring cracks,and ultimately assumes the configuration of the formed end 20. Thetransformation occurs in a rotary forming machine B. The rotary formingmachine B includes (FIGS. 5 and 6) a frame 90 which carries a table 92that rotates about a vertical axis Y.

Actually, the table 92 rotates on a base 94 with the power for producingthe rotation being supplied by a motor, either electric or hydraulic,that is in the base 94. The base 94 follows vertical ways 96 on theframe 90, with this translational movement deriving from a ram 98 thatis located between the bottom of the frame 90 and the base 94. The ram98 contains a load cell for measuring the force exerted by it. The table92 has an upwardly presented surface out of which a socket 100 opens,and the socket 100 is configured to receive the pilot diameter 12 andthe flange 10 of the pre-form 70, with the axis X of the pre-form 70coinciding with the axis Y of rotation for the table 92, and with thespindle 14 projecting upwardly. The socket 100 also receives the lugbolts 16 as well, and they engage the pre-form 70 with the table 92 suchthat the pre-form 70, when on the table 92, will rotate with the table92 without slipping.

The machine B also includes a cross head 110 which is mounted on theframe 90 by means of trunnions 112, the common axis Z of whichintersects the axis Y for the table 92 at a right angle. The cross head110 has a spindle 114 which rotates about an axis S that intersects thetrunnion axis Z and the table axis Y, with its inclination as to theaxis Y being variable and dependent on the position of the cross head110. That position is controlled by an electric screw jack 116 which isconnected between the cross head 110 and the frame 90. The cross head100 carries a motor, either electric or hydraulic, which rotates thespindle 114.

At its lower end, the spindle 114 has a forming tool 120 attached to it,and the tool 120 has a contoured face 122 (FIG. 7) that is presentedtoward the table 92 so that it will bear against the end portion 71 ofthe spindle 14 on the pre-form 70 as the table 92 is elevated. Thecontour leaves the tool 120 with a peripheral rib 124 and a depressedcenter region having a flat surface 126 that merges with the rib 124along an arcuate surface 128 which matches the curvature of the curvedend surface 60 on the formed end 20.

Finally, the machine B has a restraining arm 140 which at one end isattached to a post 142 that rises from the base 94 to an elevation abovethe table 92. At its other end the arm 140 is configured to fit againstone of the flanges 46 of the housing 4 for the particular hub assembly Athat is in the socket 100 of the table 92. The arm 140 prevents thehousing 4 from rotating with the hub 2 when the table 92 revolves. Underthe circumstances the flange 46 of housing 4 serves as a torque arm. Therestraining arm 140 extends over the table 92 generally perpendicular tothe torque arm formed by flange 46 and contains a sensor 144 formeasuring the force exerted on the arm 140 by flange 46 of the housing4. Hence, the sensor 144 enables one to measure the torque exerted onthe housing 4 by the rotating hub 2.

In order to complete the hub assembly A from its component parts, someof the parts first require preassembly. For example the bolts 16 arefitted to the flange 10 on the hub 2—or more accurately to the flange 10on the pre-form 70 that eventually becomes the hub 2. Also, the seal 54is pressed over the rib 30 of the outboard cone 26. Thereupon, theoutboard cone 26 is pressed over the straight spindle 14 on the pre-form70 to its fullest extent, that is until its back face 32 abuts theshoulder 18 at the end of the spindle 14. After a lubricant is appliedto the outboard cone 26 and the rollers 36 which surround it, thehousing 4 is lowered over outboard cone 26 and its row of rollers 34 andaligned with seal 26 on the outboard cone 26. Further advancement forcesthe seal 26 into the outboard end bore 44 and seats the rollers 36against the outboard raceway 40 of the housing 4. Next the inboard cone26 is pressed over the spindle 14 of the pre-form 70 until the extension34 at its small end comes against the end of the outboard cone 26. Thispositions the exitor ring 52 within the intervening surface 42 of thehousing 4 and seats the rollers 34 that surround the inboard cone 26against the inboard raceway 40 of the housing 4. Moreover, for allintents and purposes, it brings the bearing 6 which is so formed to theproper setting. At this time the inboard seal 54 may be pressed into theinboard end bore 44 of the housing 4 and over the thrust 30 of theinboard cone 26. At this juncture in the assembly procedure, the endportion 71 on the spindle 14 of the pre-form 70 projects well beyond theback face 32 of the inboard cone 26.

Once the housing 4 and bearing 6 have been fitted to the pre-form 70,the partially completed assembly is transferred to the machine B topermanently unite the hub 2, housing 4 and bearing 6. In this regard,the pre-form 70 that becomes the hub 2 is fitted to the socket 100 inthe table 92 of the machine B with the pilot diameter 12 on the pre-form70 presented downwardly and serving to position the pre-form 70 with itsaxis X coinciding with the axis Y of rotation for the table 92. Thebolts 16 in the flange 10 of the pre-form 70 project downwardly,engaging the table 92, so that when the table 92 revolves, the pre-form70 rotates without slipping.

The table 92 does indeed revolve, it being turned by the motor in thebase 94. The forming tool 120 likewise turns in the same direction,although at a lesser velocity, and it is powered by the motor in thecrosshead 110. Next the ram 98 is energized, and it elevates therotating table 92 and the partially assembled hub assembly A that is onit. The extended end portion 71 of the spindle 14 comes against therotating forming tool 120 of the crosshead 110, and the tool 120 deformsthat end portion 71 to displace the metal that is in it radiallyoutwardly and axially toward the cone 26. This deformation creates theformed end or 20. The end portion 71 is thus subjected to both radialand axial deformation which in turn produces desirable work hardening ofthe end portion 71 as enabling the formation of both curved and flatouter surfaces on the formed end with a reduced risk fracture.

More specifically, the end portion 71 of the spindle 14 aligns with theflat surface 126 on the contoured face 122 of the tool 120, and as thespindle 14 advances along the axis Y, the flat end surface 78 on the endportion 71 comes against flat surface 126 of the tool 120. Continuedadvancement of the spindle 14 causes the end portion 71 also to turnradially outwardly toward the arcuate surface 128 on the face 122 of thetool 120. As a consequence, the tapered surface 74 and thereafter thetapered surface 72 on the end portion 71 come against the flat surface126 of the tool 120. Eventually, with continued advancement of the endportion 71 into the tool 120, the end portion 71 deforms outwardly toassume the configuration of arcuate surface 128, while the adjoiningregion becomes flat, owing to its presence against the flat surface 126on the tool 120. This accounts for the curved end surface 60 and theadjacent flat surface 62 on the formed end 20 that is imparted to thespindle 14.

The ram 98 does not advance the spindle 14 into the tool 120 at aconstant velocity. Initially, the velocity is greater than near the end.Thus, the ram 98 advances more slowly as it works the metal of the endportion 71 against and along the back face 32 of the inboard cone 26.Moreover, as the ram 98 advances, the force exerted by it is registeredby the load cell in the ram 98 and is monitored. The ram 98 dwells afterthe final increment of advance to insure that the formed end 20 formedby the tool 120 retains the desired configuration. For a hub 2 with itsspindle 14 having a 45 mm outside diameter, the force exerted by the ram98 preferably should be between 6 and 8 tonnes and should not exceed 10to 12 tonnes.

The forming tool 120, as the spindle 14 on the pre-form 70 advances intoit, causes the metal of the pre-form 70 to displace gradually or, inother words, flow. To this end, the metal of the pre-form 70 must havesufficient ductility to undergo the flow without developing cracks orfissures. 1040 steel which has a sulfur content less than 0.05% byweight and preferably less than 0.02% has this capacity. The deformationwork hardens the steel, so the hardness of the formed end 20 is somewhatgreater than the hardness of the remainder of the hub 2.

The configuration of the extended portion 71 of the pre-form 70, thedistance it projects beyond the back face 32 of the inboard cone 26, andadvance imparted to the table 92 by the ram 98 are all such that theformed end 20 does not deform the inboard cone 26 or impart excessivepreload to the bearing 6. For example, if the end portion 71 of thepre-form 70 extends too far beyond the back face 32 of the inboard cone26 or otherwise contains excessive material in that region, the spacebetween the forming tool and the cone back face 32 cannot accommodateall of the material, and the inboard cone 26 undergoes distortion in theregion of its thrust rib 30 and raceway 28. Likewise, if the dwellheight of the ram 98 is too high, again inadequate space exists tocontain the metal which flows along the cone back face 32 and the cone26 will experience distortion.

Visual inspections of the formed end 20 will not reveal if it hasdistorted the inboard cone 26. But the torque in the bearing 6 will, andthe sensor 144 in the restraining arm 140 in effect measures thattorque. Moreover, the sensor 144 reveals the torque without having toremove the hub assembly A to another fixture for a separate test, andthus immediately identifies a hub assembly A which should be rejected.For a bearing 6 that fits around a hub spindle 14 with a 45 mm diameter,the maximum torque in the bearing should not exceed 35 to 40 in-lbs. Thechange in torque during the rotary forming should not exceed 8 to 10in-lbs.

The force registered by the load cell in the ram 98 also serves toidentify bearing assemblies that require rejection. In this regard,excessive force exerted by the ram indicates an error in the geometry ofthe pre-form 71 or perhaps, an error in setting up the machine B. In anyevent, excessive force exerted by the ram 98 may distort the inboardcone 26, causing permanent damage to the bearing assembly A. For a hub 2having a spindle 14 with a 45 mm outside diameter, a ram force exceeding10 to 12 tonnes signals a possible defect.

The restraining arm 140 not only facilitates measurement of the torque,but it also holds the housing 2 fixed while the hub 2 and rollers 36rotate within it. This seats the rollers along the raceways 28 andagainst the thrust ribs 30 of the two cones 26 and also seats them alongthe raceways 40 of the housing 4. It further prevents brinnelling of theraceways 28 and 40.

In lieu of the outboard cone 26 being a separate component, it may beintegrated into the hub 2. In other words, the outboard inner raceway 28may be formed directly on the spindle 14, just as the outer raceways 40are formed directly on the housing 4 On the other hand, the outerraceways 40 may be formed on separate races or cups fitted into thehousing 4. The rolling elements need not be tapered rollers 36, but maybe balls or other rolling elements well known in the art, and of coursethe raceways in that instance would conform to them, yet preferablyremain oblique to the axis.

In view of the above, it will be seen that the several advantages of thepresent invention have been achieved and other advantageous results havebeen obtained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A spindle having an outer cylindrical spindlesurface and an axial end bore with an inner cylindrical spindle surface,the spindle having a radial spindle thickness between said inner andouter cylindrical spindle surfaces, the spindle having a deformableannular end portion with internal and outer surfaces and a terminal endsurface, the outer surface of the deformable annular end portion being acontinuation of the outer cylindrical spindle surface, the deformableend portion having a radial thickness between its internal and outersurfaces that is less than the radial spindle thickness, the internalsurface of the deformable end portion being spaced radially outwardly ofthe inner cylindrical spindle surface and merging into the innercylindrical spindle surface along a straight beveled surface, thedeformable end portion having a tapered inner surface that tapersinwardly along at least a portion of the length thereof from saidterminal end surface toward said beveled surface so that said deformableend portion gradually increases in thickness along at least a portion ofthe length thereof from said terminal end surface toward said beveledsurface.
 2. The spindle of claim 1 wherein said tapered inner surfaceextends the entire length of said internal surface of said deformableend portion.
 3. The spindle of claim 2 wherein said tapered internalsurface includes at least two different tapers, one of the tapers beingadjacent the terminal end surface and sloping outwardly at an angle tothe spindle axis at a greater angle than the other of the tapers.
 4. Aspindle having inner and outer spindle surfaces and a rotational axis,the spindle having a deformable annular end portion with internal andexternal surfaces and a terminal end surface, the external surface ofthe deformable annular end portion being a continuation of the spindleouter surface and the internal surface of the deformable annular endportion being spaced radially outwardly from the spindle inner surface,characterized in that the internal surface of the deformable annular endportion has a tapered surface that extends along at least a portion ofits length from the terminal end surface of the deformable annular endportion and is inclined inwardly toward the rotational axis from theterminal end surface so that the deformable annular end portiongradually increases in radial thickness along at least a portion of itslength axially inwardly from the terminal end surface, and wherein astraight beveled surface extends outwardly from the spindle innersurface at an oblique angle to the spindle rotational axis and mergeswith the internal surface of the deformable annular end portion at alocation such that when the deformable annular end portion is outwardlydeformed to have its external surface extend outwardly in a directionaway from the rotational axis and intersect with the spindle outersurface at an inside corner, the location of the merger between thestraight beveled surface and the internal surface of the deformableannular end portion is generally diagonally opposite from the insidecorner.
 5. The spindle of claim 4 wherein the tapered surface is a firsttapered surface and the internal surface of the deformable annular endportion includes a second tapered surface extending along at least aportion of the length thereof from the first tapered surface toward therotational axis.
 6. The spindle of claim 5 wherein the second taperedsurface extends along a greater portion of the length of the deformableannular end portion than the first tapered surface.
 7. The spindle ofclaim 6 wherein the second tapered surface is inclined to the spindlerotational axis at a smaller angle than the angle of inclination of thefirst tapered surface to the spindle axis.
 8. The spindle of claim 7wherein the straight beveled surface is inclined to the spindlerotational axis at a larger angle than the first tapered surface, andthe second tapered surface is inclined to the spindle axis an angle thatis smaller than the inclination angles of both the straight beveledsurface and the first tapered surface.
 9. The spindle of claim 5 whereinthe intersection between the terminal end surface and the taperedsurface is rounded.
 10. A spindle having a rotational axis and adeformable annular end portion with a terminal end surface and an innersurface, said inner surface of said deformable annular end portionincluding a tapered surface extending along at least a portion of thelength of said inner surface of said deformable end portion from theterminal end surface toward the rotational axis, said tapered surfacebeing inclined inwardly toward the rotational axis in a direction fromthe terminal end back inwardly into the annular end portion, and theintersection between the terminal end surface and the first taperedsurface being rounded.
 11. The spindle of claim 10 wherein the taperedsurface is a first tapered surface and the inner surface of thedeformable annular end portion includes a second tapered surface that isoutwardly deformable along with the deformable annular end portion andextends along at least a portion of the length of the inner surface fromthe first tapered surface toward the rotational axis and axially of thespindle back inwardly into the annular end portion.
 12. The spindle ofclaim 11 wherein the second tapered surface extends along a greaterportion of the axial length of the deformable annular end portion thanthe first tapered surface.
 13. The spindle of claim 12 wherein thesecond tapered surface is inclined to the spindle rotational axis at asmaller angle than the angle of inclination of the first tapered surfaceto the spindle axis.
 14. A spindle having a rotational axis and adeformable annular end portion with a terminal end surface and an innersurface, said inner surface of said deformable annular end portionincluding a tapered surface extending along at least a portion of thelength of said inner surface of said deform able end portion from theterminal end surface toward the rotational axis, said tapered surfacebeing inclined inwardly toward the rotational axis in a direction fromthe terminal end back inwardly into the annular end portion, and saiddeformable annular end portion having a cylindrical outer surface and aradial thickness that decreases along its length in a direction towardthe terminal end surface thereof.
 15. A spindle having a rotational axisand a deformable annular end portion with a terminal end surface and aninner surface, said inner surface of said deformable annular end portionincluding a tapered surface extending along at least a portion of thelength of said inner surface of said deformable end portion from theterminal end surface toward the rotational axis, said tapered surfacebeing inclined inwardly toward the rotational axis in a direction fromthe terminal end back inwardly into the annular end portion, saidtapered surface being a first tapered surface and the inner surface ofthe deformable annular end portion including a second tapered surfaceextending along at least a portion of the length thereof from the firsttapered surface toward the rotational axis, said spindle including aninner beveled surface inclined to the rotational axis and intersectingsaid second tapered surface at the axial inner end of said deformableannular end portion, said inner beveled surface being inclined to thespindle rotational axis at a larger angle than the first taperedsurface, and the second tapered surface being inclined to the spindleaxis at an angle that is smaller than the inclination angles of both thebeveled surface and the first tapered surface.
 16. A spindle having arotational axis and a deformable annular end portion with a terminal endsurface and an inner surface, said inner surface of said deformableannular end portion including a tapered surface extending along at leasta portion of the length of said inner surface of said deformable endportion from the terminal end surface toward the rotational axis, saidtapered surface being inclined inwardly toward the rotational axis in adirection from the terminal end back inwardly into the annular endportion, and said terminal end surface of said deformable annular endportion being flat.
 17. The spindle of claim 11 wherein said spindleincludes an inner beveled surface that is inclined to the rotationalaxis and intersects said second tapered surface at the axial inner endof said deformable annular end portion.